Systems and methods for retrieving an implantable device

ABSTRACT

The present disclosure provides systems and methods for retrieving an implantable device. An implantable device includes a casing, and a marker coupled to the casing, wherein the marker includes a detectable material encased in a biocompatible material, and wherein the marker facilitates accurately locating and retrieving the implantable device after implantation in a patient.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/050,896, filed Feb. 23, 2016, which claims the benefit of U.S.Provisional Application Ser. No. 62/215,622, filed Sep. 8, 2015.

A. FIELD OF THE DISCLOSURE

The present disclosure relates generally to implantable cardiac monitors(ICMs), and more particularly to systems and methods for implantingICMs.

B. BACKGROUND ART

Implantable cardiac monitors (ICs) are devices that may be implantedunder a patient's skin to continuously monitor the patient's cardiacactivity. An ICM may be programmed to detect and record cardiacinformation and episodes such as atrial/ventricular tachycardia, atrialfibrillation, bradycardia, asystole, etc. Triggers for detecting andrecording an event (e.g., such as a tachy/brady detection rate, a numberof events, and/or a duration of asystole) may be programmed by aclinician. Alternatively, when the patient experiences symptoms, thepatient may activate the detection and recording using an externalpatient activator. Diagnostics and recorded events may be downloaded bythe clinician in-clinic using a programmer. Further, the data may alsobe transmitted to the clinician using a daily remote monitoring system.

ICMs are generally relatively small (e.g., 1.1-1.5 cm³ in volume), andcan be implanted using a relatively small incision (e.g., 1 cm). Onceinserted under the patient's skin, the ICM has a relatively slimprofile, mitigating patient concerns about body image. The ICM may beimplanted in the patient's chest area near the sternum, and the implantprocedure may take less than 10 minutes after application of a localtopical anesthesia. Further, ICMs do not deliver pacing or shocktherapies to the patient, nor do they require leads to be implanted inthe patient's heart.

After a period of time, implanted devices, such as an ICM, may need tobe retrieved from a patient. For example, an implanted device may beretrieved if a battery of the device fails, a diagnosis performed usingthe device is complete, or the device is causing an infection. Animplanted device may also be retrieved for cosmetic purposes. Notably,in at least some known systems, given the size of the implantabledevice, it may be relatively difficult to locate and retrieve thedevice. For example, in at least some known systems, a physician takesx-rays of the patient in an attempt to determine a generation locationof the device, makes an incision (which may or may not be proximate thedevice) based on the x-rays, and attempts to grab and remove the device.

BRIEF SUMMARY OF THE DISCLOSURE

In one embodiment, the present disclosure is directed to an implantabledevice. The implantable device includes a casing, and a marker coupledto the casing, wherein the marker includes a detectable material encasedin a biocompatible material, and wherein the marker facilitatesaccurately locating and retrieving the implantable device afterimplantation in a patient.

In another embodiment, the present disclosure is directed to animplantation system. The implantation system includes an implantabledevice including a casing, and a marker coupled to the casing, whereinthe marker includes a detectable material encased in a biocompatiblematerial, and wherein the marker facilitates accurately locating andretrieving the implantable device after implantation in a patient. Theimplantation system further includes an insertion tool configured toimplant the implantable device in the patient.

In another embodiment, the present disclosure is directed to a methodfor retrieving an implanted device from a patient. The method includeslocating a marker included within the implanted device by detecting adetectable material encased in a biocompatible material and includedwithin the marker, making an incision in skin of the patient proximatethe located marker, and retrieving the implanted device through theincision.

The foregoing and other aspects, features, details, utilities andadvantages of the present disclosure will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of one embodiment of an implantablecardiac monitor (ICM).

FIG. 2 is a schematic diagram of the ICM shown in FIG. 1 implanted in apatient.

FIG. 3 is a schematic diagram of one embodiment of a marker that may beused with the ICM shown in FIG. 1.

FIGS. 4A-4D are schematic diagrams illustrating operation of oneembodiment of a system for implanting the ICM shown in FIG. 1.

FIGS. 5A-5F are schematic diagrams illustrating operation of oneembodiment of a system for implanting the ICM shown in FIG. 1.

FIG. 6 is a schematic diagram of an alternative embodiment of an ICM.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides systems and methods for retrieving animplanted device. An implantable device includes a casing, and a markercoupled to the casing, wherein the marker includes a detectable materialencased in a biocompatible material. Once implanted, the marker can bedetected to facilitate locating and retrieving the device.

The systems and methods described herein facilitate retrievingrelatively small injectable devices that have previously been implantedin a patient. Injectable devices that are retrievable using the systemsand methods described herein may include, for example, an implantablecardiac monitor (ICM), a birth control device, and a leadless pacemaker.Although embodiments directed to an ICM are described herein in detail,those of skill in the art will appreciate that similar systems andmethods may be implemented for retrieving other types of injectabledevices.

At least some embodiments described herein include a marker attached toan injectable device (e.g., with a suture) and positionable just underthe skin of the patient. A dilator and/or other insertion tool may beused to inject the device. A device finder allows a physician to locatethe injectable device and mark the location of the injectable device onthe skin of the patient. Once the injectable device is located, the skinjust over the marker may be cut, and a tool (e.g., a hemostat) may beused to retrieve the injectable device. In some embodiments, a suture iscoupled to the marker, and a dilator may be used to follow the sutureand create a tunnel to the injectable device, such that the suture canthen be pulled to retrieve the device through the tunnel.

Referring now to the drawings and in particular to FIG. 1, animplantable cardiac monitor (ICM) is indicated generally at 100. ICM 100includes a proximal pickup electrode 102 that may be made of abiocompatible metal (BCM), such as titanium, 304 stainless steel, or 316stainless steel. Proximal pickup electrode 102 is attached to a casing104 using a suitable epoxy 106. Casing 104 may also be made of a BCM.For operation of ICM 100, in this embodiment, casing 104 includescircuitry, a battery, and a receiving and transmitting antenna. Casing104 is insulated with a coating (e.g., a parylene coating) with theexception of a distal portion 108. Distal portion 108 functions as acounter electrode to proximal pickup electrode 102 for detectingelectrocardiograms. Proximal pickup electrode 102 is connected tocircuitry in casing 104 using a feedthrough pin 110, as will beunderstood by those of skill in the art.

In this embodiment, ICM 100 includes a marker 112 that couples toproximal pickup electrode 102. For example, marker 112 may engageproximal pickup electrode 102 in a snap-fit configuration. Marker 112may also be tied to proximal pickup electrode 102 using a suture (notshown in FIG. 1), as described below. Marker 112 is a BCM at leastpartially filled with a detectable material in this embodiment. Thedetectable material may include, for example, a ferrous material such assoft iron, or a permanent magnet made of sintered neodymium-iron-boronor a similar material. The permanent magnet is protected from bodyfluids because marker 112 encloses the permanent magnet in a BCMhousing.

Because marker 112 includes the detectable material, marker 112 can bedetected, and thus located, under the skin of a patient. For example, ifmarker 112 is filled with soft iron, a miniature metal detector with aloop coil having a diameter of approximately 1-2 centimeters (cm) orless may be used to locate marker 112 below a surface of the skin. Metaldetectors are well-known and operate by detecting a small shift in aresonant frequency of a circuit that includes a loop coil, the shiftcaused by proximity of a material (e.g., soft iron) that alters aninductance of the loop coil.

If marker 112 includes a permanent magnet, a giant magnetoresistance(GMR) sensor may be used to locate the permanent magnet, and thus marker112, under the skin. The larger the magnetic field detected by the GMRsensor, the closer the GMR sensor to marker 112.

FIG. 2 is a schematic diagram of ICM 100 implanted in tissue 202, belowthe skin 204 of a patient. As shown in FIG. 2, ICM 100 is implantedrelatively deep beneath skin 204, but marker 112 has disengaged fromproximal pickup electrode 102 (i.e., from a snap-fit engagement).However, marker 112 is still connected to proximal pickup electrode 102via a suture 208. Further, marker 112 is relatively near the surface ofskin 204. Depending on what material marker 112 includes, marker 112 maybe located, for example, using a metal detector or GMR sensor, asdescribed above.

Once marker 112 is located, a small incision (e.g., 3 millimeters (mm))may be made in skin 204, and marker 112 may be grabbed (e.g., using ahemostat) and pulled through the incision. In this embodiment, suture208 may be a high tensile strength non-absorbable material suture thathas a pull tensile strength of approximately a 5 kilogram (kg) force.Alternatively, suture 208 may have any suitable composition and/orproperties. Once marker 112 is pulled through the incision, suture 208can be pulled on (e.g., using a hemostat) to extract ICM 100 from thepatient through the incision. The incision is then dosed (e.g., using atissue adhesive).

In some embodiments, marker 112 includes a material such as soft iron oran encapsulated permanent magnet (e.g., a neodymium magnet), such thatthe person explanting marker 112 may simply sweep the skin above theimplant site using a strong permanent magnet (e.g., a neodymium magnet).When the explanter feels a force on the sweeping magnet, the explanterknows the sweeping magnet is near marker 112. If marker 112 incorporatesa permanent magnet, then the explanter may simply sweep above theexpected implant area with a ferromagnetic material such as soft iron.Again, the marker will cause a force to be exerted on the ferromagneticmaterial, but the force may not be as strong as when using a permanentmagnet as the sweeping magnet. In yet another embodiment, marker 112 ismade of a simple ferromagnetic material (i.e., not a permanent magnet),and the sweeper magnet may be a strong permanent magnet.

In some instances, ICM 100 may be not be easily extracted by pulling onsuture 208. Accordingly, in such circumstances, a suture extension (notshown) may be tied to suture 208 and threaded through a dilator. Thedilator can then be used to push through the tissue 202 along the pathof suture 208, creating a channel or path through tissue 202 to ICM 100.Once the channel is established, ICM 100 may be easily extracted byapplying a relatively slight pull to suture 208.

FIG. 3 is a schematic diagram of marker 112. As described above, marker112 is encapsulated by a BCM 302 and includes a detectable material 304therein (e.g., a ferrous metal or a permanent magnet). As shown in FIG.3, in this embodiment, marker 112 includes a bobbin portion 306 thatdefines an annular recess 308. To couple marker 112 to suture 208,suture 208 may be coiled around or tied to bobbin portion 306. Bobbinportion 306 may be shaped to engage proximal pickup electrode 102 (e.g.,in a snap-fit engagement).

FIGS. 4A-4D are schematic diagrams of operation of a system 400 forimplanting ICM 100. Specifically, system 400 includes ICM 100 and aninsertion tool 401. Insertion tool 401 includes an injector housing 402and an obturator 404. Injector housing 402 includes a substantiallycylindrical tube 408 that extends from a first end 410 to a second end412. Tube 408 includes a first tube portion 414 proximate first end 410and a second tube portion 416 proximate second end 412. In theillustrated embodiment, first tube portion 414 has an inner diameterthat is slightly smaller than an inner diameter of second tube portion416. Alternatively, first and second tube portions 414 and 416 may havesubstantially the same inner diameter. Both first and second tubeportions 414 and 416 have inner diameters that are larger than adiameter of ICM 100, such that ICM 100 is positionable within tube 408,as described in detail herein. Second end 412 includes an opening 417 tofacilitate inserting obturator 404 into injector housing 402. Injectorhousing 402 includes another opening 418 at first end 410 to facilitatedischarging ICM 100 from injector housing 402 into the patient.

In some embodiments, injector housing 402 includes an indicator (notshown), such as a colored band, proximate first end 410. The indicatorfacilitates aligning injector housing 402 during an implantationprocedure, as described herein. Injector housing 402 may be fabricatedfrom, for example, polycarbonate, polysulfone, or another similarlyresilient material.

Injector housing 402 further includes a receptacle 420 in communicationwith second tube portion 416 and in communication with the externalenvironment. As shown in FIG. 4A receptacle 420 is sized to receive ICM100. In the illustrated embodiment, receptacle 420 includes one or moreprojections that facilitate preventing ICM 100 from falling out ofreceptacle 420 into the external environment. For example, theprojections may engage ICM 100 in a snap-fit engagement to facilitatemaintaining ICM 100 in receptacle 420. As shown in FIG. 4A, when ICM 100is inserted into receptacle 420, obturator 404 is already inserted intofirst and second tube portions 414 and 416. Accordingly, obturator 404initially prevents ICM 100 from entering second tube portion 416.

Obturator 404 includes a substantially cylindrical shaft 430 thatextends from a first end 432 to proximate a second end 434. An obturatorhandle 436 is formed at second end 434 of obturator 404. Obturatorhandle 436 has a diameter that is larger than the diameter ofcylindrical shaft 430 and the inner diameter of second tube portion 416.A tip 439 is formed at first end 432 of obturator 404. Tip 439 isconfigured to perform blunt dissection in subcutaneous tissue 202 of thepatient. Tip 439 may have any shape that enables obturator 404 tofunction as described herein. Obturator 404 may be fabricated from, forexample, polycarbonate, polysulfone, or another similarly resilientmaterial.

A method of implanting ICM 100 using injection system 400 will now bedescribed with respect to FIGS. 4A-4D. An incision (e.g., a 6 millimeter(mm) incision) is made in the patient using, for example, a surgicalscalpel. With obturator 404 inserted into injector housing 402 and ICM100 inserted into receptacle 420, injector housing first end 410 isinserted through the incision into the patient's tissue. As shown inFIG. 4B, tip 439 extends beyond first end 410 and provides a relativelysmall spear-shaped entry point into the tissue. At this point, tip 439is used to perform blunt dissection in subcutaneous tissue of thepatient, in preparation for the deployment of ICM 100. To form acylindrical channel for ICM 100 below the patient's skin, the injectorhousing may be advanced until receptacle 420 reaches the incision.

Once blunt dissection is completed, as shown in FIGS. 4C and 4D,obturator 404 is pulled back partially out of injector housing 402 in afirst direction towards injector housing second end 412), as shown inFIG. 4B. Once tip 439 passes ICM 100 and receptacle 420, ICM 100 drops(i.e., due to gravity) from receptacle 420 into second tube portion 416.

FIGS. 5A-5F are schematic diagrams illustrating operation of system 400to finalize the implant process. As shown in FIG. 5A, system 400includes a pushing tool 440 including a substantially cylindrical shaft442 that extends from a first end 444 to proximate a second end 446. Ahandle 448 is formed at second end 446 of pushing tool 440. Handle 448has a diameter that is larger than the diameter of cylindrical shaft 442and the inner diameter of second tube portion 416. A cup-shaped recess450 is formed in first end 444. Recess 450 is configured to surround andengage marker 112 (e.g., in a snap-fit engagement).

As shown in FIG. 5B, after ICM 100 has dropped into second tube portion416, pushing tool 440 is inserted into second tube portion 416 such thatrecess 450 engages marker 112. Notably, injector housing 402 has beenpulled back from tissue 202 to allow ICM 100 to be inserted into thechannel formed by obturator 404 by advancing pushing tool 440, as shownin FIG. 5C.

As shown in FIG. 5D, once ICM 100 is deposited in tissue 202, pushingtool 440 and marker 112 are retracted, disengaging marker 112 fromproximal pickup electrode 102 and exposing suture 208. By applying asmall force to pushing tool 440, marker 112 may be disengaged frompushing tool 440 such that marker 112 remains in tissue 202, relativelyclose to the surface of skin 204, as shown in FIG. 5E. In the event thatmarker 112 actually exits the skin insertion site, the person performingthe implantation procedure may simply wrap any excess length of suture208 around bobbin portion 306. FIG. 5E illustrates the finalimplantation position of ICM 100 once the insertion site has been closed(e.g., using tissue adhesive).

FIG. 6 is a schematic diagram of an alternative embodiment of an ICM600. Unless otherwise noted, ICM 600 is substantially similar to ICM100. As compared to ICM 100, instead of including a separate marker, ICM600 includes a detectable material (e.g., a ferromagnetic material or apermanent magnet) in proximal pickup electrode 602. Accordingly, a metaldetector or GMR sensor may be used to locate ICM 600 using techniquessimilar to those discussed above in relation to ICM 100.

Although the embodiments described herein discuss using a ferromagneticmaterial or permanent magnet as the detectable material, those of skillin the art will appreciate that other materials may also be used. Forexample, in one embodiment, suture 208 and/or marker 112 includes afluorescent compound. If suture 208 and/or marker 112 is left near thesurface of skin 204, a black light may be used to locate ICM 600, suchthat ICM 600 can be explanted as described herein. In other embodiments,the detectable material may be a plastic material detectable byobserving a change in dielectric properties or a change in conductivitywhile running a relatively current through the patient's skin. In stillother embodiments, the ICM may include an antenna that broadcasts adetectable signal (e.g., in a medical implant communication service(MICS) band) to facilitate locating the ICM.

In yet another embodiment, suture 208 may be made of a conductive metalwire or cable, and may be connected through a feed through to acommunication band (e.g., medical implant communication service (MICS)or Bluetooth) to act as an antenna to provide for enhanced communicationcapability. The same feedthrough or a second feedthrough may be used toprovide for a connection. For example, the communication distance may beincreased 10 to 100% or more. Accordingly, suture 208 may providemultiple functions, including functioning as an antenna for enhanceddata communications, and functioning as a means for locating the implantfor explantation. For example, using a receiver to sweep in proximity ofthe implanted device, the explanter can use signal strength to preciselylocate the implant site. Suture 208 may be used to pull and extract thedevice from tissue at explant. Notably, an ICM antenna is typicallyembedded in epoxy 106 adjacent to proximal pickup electrode 102.However, this is a relatively confined location. Accordingly, usingsuture 208 as the ICM antenna can increase the antenna size and thusenhance communication abilities.

Further, in some embodiments, proximal pickup electrode 102 may beincorporated as part of marker 112. This provides a larger pickup dipoleas compared to including proximal pickup electrode 102 as part of ICM100, which increases the ECG signal and improves the performance of theICM by increasing the signal to noise ratio. Suture 208 may incorporatetwo connective elements one for the antenna and one for connection tothe ECG electrode or ECG which is relatively low-frequency (e.g., 0.2 to100 Hz) as compared to hundreds of KHz in to the GHz range for RF).

In embodiments where marker 112 includes a magnetic material, a magnetictool (e.g., a magnetized hemostat) may be used. Further, in someembodiments, marker 112 includes a loop, or handle, that is engageableby a hemostat to facilitate retrieval.

The systems and methods described herein facilitate relativelystraightforward locating and retrieval of an implanted device, such asan implantable cardiac monitor. The implanted device includes markerhaving a detectable material, such as a ferrous material or a permanentmagnet that may be detected by an instrument. Once detected, an incisionmay be made proximate the marker, and the implanted device may beremoved through the incision.

Although certain embodiments of this disclosure have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this disclosure. All directionalreferences (e.g., upper, lower, upward, downward, left, right, leftward,rightward, top, bottom, above, below, vertical, horizontal, clockwise,and counterclockwise) are only used for identification purposes to aidthe reader's understanding of the present disclosure, and do not createlimitations, particularly as to the position, orientation, or use of thedisclosure. Joinder references (e.g., attached, coupled, connected, andthe like) are to be construed broadly and may include intermediatemembers between a connection of elements and relative movement betweenelements. As such, joinder references do not necessarily infer that twoelements are directly connected and in fixed relation to each other. Itis intended that all matter contained in the above description or shownin the accompanying drawings shall be interpreted as illustrative onlyand not limiting. Changes in detail or structure may be made withoutdeparting from the spirit of the disclosure as defined in the appendedclaims.

When introducing elements of the present disclosure or the preferredembodiment(s) thereof, the articles “a”, “an”, “the”, and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including”, and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions withoutdeparting from the scope of the disclosure, it is intended that ailmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. A method for retrieving an implanted device froma patient, the method comprising: locating a marker included within theimplanted device, wherein the marker comprises a detectable materialencased in a biocompatible material, wherein the marker is located bydetecting the detectable material; after locating the marker, making anincision in skin of the patient proximate the marker; and retrieving theimplanted device through the incision, wherein the implanted devicefurther comprises a casing and a proximal pickup electrode coupled tothe casing; and wherein the marker is configured to disengageably coupleto the proximal pickup electrode in a snap-fit configuration, andwherein the marker is tethered to the proximal pickup electrode with asuture.
 2. A method in accordance with claim 1, wherein the markercomprises a ferrous material.
 3. A method in accordance with claim 2,wherein locating the marker comprises detecting the ferrous materialusing a metal detector.
 4. A method in accordance with claim 1, whereinthe marker comprises a permanent magnet.
 5. A method in accordance withclaim 4, wherein locating the marker comprises detecting the permanentmagnet using a giant magnetoresistance sensor.